Draftsman&#39;s compass



Sept. 7, 1948. F. FULLER DRAFTSMANS COMPASS Filed NOV. 17, 1944 kmx m M M WW KW m a M A E M fl g w ///N/ Patented Eept. 7, 1948 warren STATES;

NT, orrics 2 Claims. 1

This invention relates to drawing instruments and particularly to draftsmans compasses, and has for its object a compass by which different forms, circular or non-circular, may be drawn from a 'teniplet or form plate applied to or embodied in the compass.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

Figure 1 is an elevation, partly in section, of

and secured thereto, so as not to be rotatable relatively to the shaft, the form plate having a guide or cam of the contour of the figure to be drawn, a drawing point or stylus-carrying leg, that is, a pen or pencil-carrying leg, having a follower movable along the guide or cam during the revolution of the leg about the axis of the stationary shaft, and a support for the leg rotatably mounted on the shaft to hold the leg with its follower engaged with the guide of the form plate.

I designates the centering shaft pointed at its lower end for pricking the paper on which the drawing is to be made, the shaft having a knurled head 2 at its upper end by which it can be easily held from turning or shifting about its axis. 3 designates the form plate or templet, this being shown as having a hub 4 slidably mounted to shift axially on the centering shaft 5 but held from relative rotary movement, by a suitable key, as a pin 5 extending through a lengthwise slot 5 in the hub 4 into the shaft l. The form plate 3 is formed with a guide or cam l on its lower face of the contour of the figure to be reproduced. The guide, as here shown, is elliptical, but obviously it may be of any other shape.

8 designates the drawing-point leg of the compass, that is, the leg carrying the stylus, pencil or pen, this having a follower, as a ball 9 at its upper end movable in the guide I of the form plate. The leg is rotatably supported from the centering shaft l" and the leg 5% coacts with its support to have a radial shifting movement, as the follower moves radially in conforming with the major and minor dimensions or diam-- eters of the cam guide of the form plate. l0 designates the support, this including a hub ii rotatably mounted on the centering shaft l above the form plate Band having a radial arm extendingover the form plate, an angular arm H! extending crosswise of the edge of the form plate, and a radial arm I?! extending inwardly under the form plate from the angular arm, the arm l2 being formed with a lengthwise guide slot orgroove it for receiving a sliding head M on the leg 8- to permit and guide the radial shifting movementrof the leg 8. The hub H is provided with a knurled head I I'll for facilitating theturning of the support about the shaft I.

For the purpose of locating the follower 9 in the guide of the form plate or removing it therefrom, the arm I2 is adjustably mounted on the angular arm to move toward and from the form plate 3, and as here shown, the arm 12 is pivoted to the lower end of the angular arm and held in its adjusted position, as by a clamp screw I40.

The leg 8 is composed of sections hinged together at it, the lower section being adjustable about the pivot l5 radially, in order to vary the scale or size of the figure to be drawn with respect to that of the guide I. The lower section it of the leg is held in its adjusted position, as by a screw and nut at IT. The lower section [6 of the leg is braced during its revolution about the centering shaft l by an adjustable or folding brace 68 secured at l9 to the lower section of the leg and having a collar 29 rotatably mounted on the centering shaft l but held from enclwise movement, the shaft being here shown as formed with a circumferential groove 2i and the collar as with a pin or follower movable into the groove. The brace i8 steadies the leg 8 or holds it from lateral movement, but permits the leg to shift radially as the follower or ball ii follows the guide or cam of the form plate.

In operation, with the centering shaft l properly located on the paper and a form plate with a guide of the form to be reproduced, the lower section of the stylus-carrying leg being adjusted radially to produce the figure of the desired size the operator applies some axial pressure to the shaft l and holds it from turning, while turning the hub H by means of its knurled head, thus moving the support it and hence the leg 8 about the centering shaft to reproduce on the paper a figure of the contour of the guide of the form plate. Obviously, form plates with guides of various contours are interchangeably mountable on the shaft I.

What I claim is:

1. A draftsmans compass comprising a, centering shaft pointed at its end, a form plate mounted on the shaft and having a guide of the contour of the figure to be drawn and being non-rotatable relatively to the shaft, a styluscarrying leg having a follower movable along the guide during revolution of the leg around the axis of the shaft, a support for the leg rotatably mounted on the shaft to revolve the leg around the shaft, said supporting including a guide for permitting radial shifting of the leg as the follower moves along portions of the guide of the form plate nearer or farther from the axis of the shaft, said support including a hub rotatably mounted on the shaft, an arm extending radially from the hub and having an angular portion extending crosswise of the edge of the form plate and an inwardly extending arm extending under the form plate and formed with a slot, said leg having a follower movable in the slot, the inwardly extending arm being adjustable toward and from the form plate to permit the follower to be located in and removed from the guide of the form plate.

2. A draftsmans compass comprising a cen tering shaft pointed at its end, a form plate mounted on the shaft and having a guide of the contour of the figure to be drawn and being non-rotatable relatively to the shaft, a stylusoarrying leg having a follower movable along the guide during revolution of the leg around the axis of the shaft, a support for the leg rotatably mounted on the shaft to revolve the leg 4 around the shaft, said shaft including a guide for permitting radial shifting of the leg as the follower moves along portions of the guide of the form plate nearer or farther from the axis of the shaft, said support including a hub rotatably mounted on the shaft, an arm extending radially from the hub and having an angular portion extending crosswise of the edge of the form plate and an inwardly extending arm extending under the form plate and formed with a slot, said leg having a movable follower in the slot, the inwardly extending arm being adjustable toward and from the form plate to permit the follower to be located in and removed from the guide of the form plate, the leg including upper and lower sections, the lower section being adjustable radially relatively to the upper section, and a folding brace connected to the lower section and having a bearing rotatably mounted on the shaft.

FREDERICK FULLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 324,395 Marichal Aug. 18, 1885' 552,293 Kuhn Dec. 31, 1895 646,329 Tintanne Mar. 27, 1900 877,710 Goodale Jan. 28, 1908 FOREIGN PATENTS Number Country Date 105,735 Switzerland 1924 

